DE2856400A1 - WINGS, IN PARTICULAR FOR ROTARY WINGS - Google Patents

Description

PATBN TANWAtT

DIPL. ING. K.

PHIlimKB-WBLSEB-SIBASSB 14

8900 AUGSBUKQ

XBItBFOH 61647 5 TELEX 533S02 ρείο! d

2858400

M. 6 33

Augsburg, December 27, 1978

The Secretary of State for Defense in Her Britannic Majesty ^f s Government of the United Kingdom of Great Britain and Northern Ireland, Whitehall, London SWl, England

Hydrofoils, in particular for rotary wing aircraft

The invention relates to a wing according to the preamble of claim 1, in particular for rotary wing aircraft.

When constructing plug-in tools, the efficiency special attention to the wing under load

909B28 / 0785

given. The load conditions of the wings are particularly complex in rotary wing aircraft. For example, the rotor blades of a helicopter constantly subject to cyclical load fluctuations during their rotation. These load fluctuations cause vibrations that can be transmitted to the fuselage of the aircraft. The also occurring Material fatigue can be particularly dangerous if the rotor blades or their fastenings are partially made of metal.

The high speed of modern helicopter rotors results in transonic flow conditions at the blade tips of the rotor blades when the blade in question moves forward in relation to the direction of flight. The blade tip section can induce a very large drag. During the backward movement phase of the rotor blade, the air flow speed in the blade tip area is very much lower and the blade tip area can overshoot, which results in undesirable vibration phenomena and the development of noise. Another problem is that strong eddies propagate from the blade tip during rotation, which contributes significantly to the overall noise generation.

909828 / 078S

285S400

To alleviate these problems, designs have already been proposed in which the Wing tip area bent out of the cocking direction is. However, it is due to helicopter rotor blades the conflicting demands with regard to the different relationships in the forward movement and the backward movement of the respective rotor blade with respect to the flight direction difficult to achieve a noticeable improvement in performance.

In order to improve the performance of an aircraft, it is desirable that the wings be as light as possible be trained as possible. To this end, research into new materials for construction is also carried out operated by hydrofoils. Composite materials with Fibers embedded in a carrier material have proven to be particularly suitable for rotor blades. Such Rotor blades are generally produced as a laminate from several pre-impregnated layers. A careful one Orientation, of the individual layers, results in orthotropic properties while at the same time providing an essentially main bending stiffness direction running in the tensioning direction is maintained.

909828/0785

The invention is based on the object of providing a wing of the type mentioned at the outset with regard to to further develop an improvement in the blade tip ratios.

This object is achieved according to the invention by the arrangement specified in the characterizing part of claim 1 solved.

According to the invention, the main bending stiffness direction can be towards the wing leading edge or towards the wing trailing edge be distracted.

In a preferred embodiment of the invention is a substantial number of extending through the wing structure substantially in the tensioning direction Pasern in the wing tip area to a wing edge turned down. All affected fibers are preferably bent to the same extent. Of the The wing tip area can be swept and the main bending stiffness direction can be advantageous be deflected so that it increases the effect of the wing tip sweep.

909828/0785

An embodiment of the invention will be described below with reference to the accompanying drawings described in detail. It shows:

Fig. La is a plan view of a helicopter

Composite rotor blade,

Fig. Ib is a side view of the rotor blade

with upward load, and

Fig. 2 is a perspective view of the

Tip area.

Fig. La and Ib show a helicopter rotor blade 10 made of composite material, which has fibers 11 and 12 embedded in a carrier material, which in the tensioning direction pass through the rotor blade. By doing with 14 indicated blade tip area is part of the Fibers close to the blade tip from the tensioning direction to the leading edge of the rotor blade 15 bent towards the main bending stiffness direction of the rotor blade in the blade tip area deflect from the clamping direction by 15 ° to 25 °.

• 09828/07 «

If the rotor blade is driven, for example, by an upward force, as described in Pig. Ib by arrows 16 is indicated, loaded, the rotor blade bends. This deflection, for the sake of clarity, only occurs in the area of the tip of the blade is shown, causes stresses in the material of the rotor blade. For example, in the area The strands 17 lying on the upper side of the sheet are subjected to pressure, while fibers 18 running on the lower side of the sheet are exposed to pressure Train are stressed. This situation is shown in more detail in Fig. 2, in which the rotor blade in the Plane X-X 'in Figs. La and Ib is cut "

The fiber 17 shown in FIG. 2 is subjected to pressure in the direction of an arrow 19. This force in The direction of the arrow 19 can move into a component 20 in the tensioning direction and in a component that is perpendicular to the tensioning direction Component 21 can be disassembled. The fiber 18 in FIG. 2 is subjected to tensile stress in the direction of an arrow 22, and this force acting in the direction of arrow 22 can in turn be broken down into two components 23 and 24. It can therefore be seen that a pair of forces formed by the components 21 and 24 is required to achieve a To prevent twisting of the blade tip area. In the absence of this pair of forces, one would have been on the blade tip area acting uniform bending force is a twist

of the blade tip area according to the arrows T.

With the rotor blade rotating in the direction of the arrow R, the blade tip area 14 occurs in an upward direction acting force causes a twist in such a way that the angle of attack in the blade tip area is reduced. Works a downward force on the blade tip portion 14, the angle of attack in the blade tip area reduced by twisting in the opposite direction of rotation. As a result, the blade tip portion of a rotor blade can be constructed in such a way that the angle of attack in the blade tip area during the entire rotor blade revolution is essentially zero, whereby the resistance in the blade tip area, especially in the case of transonic Flow conditions, is advantageously reduced.

In an airfoil designed according to the invention, a twist occurs, which increases the load on the blade tip Attempts to weaken when the wing is a Bending stress is exposed, so that vibrations and the probability of material fatigue is reduced will. Another advantage is that the twisting of the wingtip weakens the vortices that are detached at the wingtip.

909828/0785

- ίο -

noise reduction achieved.

By carefully choosing the material and design of the wing, a wide variety of torsion characteristics can be achieved can be achieved. For example, this can affect the last few percent of the wing span limited or extended to a certain distance from the wing tip. The twist can be in both Directions are generated, and the degree of twisting can be selected in linear dependence on the applied load will.

In the construction of an airfoil according to the invention, any type of fiber or fiber device, for example, carbon fibers and / or glass fibers are used.

In addition, the entire wing is not used Composite material to be made. For example, parts of the wing can be made of metal that may or may not contribute to the wing rigidity in order to avoid wear of the wing due to the influence of foreign bodies, for example sand or dust to reduce.

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Claims (5)

PATENT ADVOCATE Dipl. Ma. E. HOLZEK PHILIPPINE -WELSEB - STBASSEi 14 8900 ATJGSBUBO TELESOX 516475 TELEX S33 202 paiol d Claims ( 1. \ Wing with the main bending stiffness direction running essentially in the tensioning direction and with a wing tip section at least partially designed as a fiber-reinforced composite construction, characterized by the fact that in the plug tip section a considerable number of pasers are arranged obliquely with respect to the tensioning direction in such a way that in the plug tip section the main bending stiffness direction is deflected from the tensioning direction to a wing edge. 2. hydrofoil according to claim 1, characterized in that that a considerable number of fibers running essentially in the tension direction in the wing tip area the tensioning direction are bent in the direction of a wing edge nin. 3. hydrofoil according to claim 1 or 2, characterized in that the Plugelspitzenabschnitt is swept. 4. Airfoil according to one of claims 1 to 3, characterized in that the composite structure Contains carbon fibers. 909828/0785 5. hydrofoil according to one of claims 1 to 3, characterized in that the composite construction contains glass fibers.